Conventional color printers record medial tone color data composed of the three primary colors, yellow, magenta, and cyan by means of the "dither method" at a predetermined resolution. When recording color data together with black/white data, if the color data is recorded using a specific resolution identical to that of the black/white information, an enormous amount of color information needs to be stored. This color information corresponds to three times the black/white data needed, thus complicating the memory control of the picture data. The human eye has a relatively high visual sensitivity to black/white data, but a low visual sensitivity to color data. Consequently, the resolution of color picture data can be lowered considerably without any detectable change in the quality of the picture itself.